<HTML dir=ltr><HEAD><TITLE>Re: [Proj] Extended range TM usage</TITLE>
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<DIV dir=ltr><FONT face="Times New Roman" color=#000000 size=2>The most common rational reasons include GIS applications of hydrocarbon-producing regions. For example, the entire Gulf of Mexico, significant portions of Siberia, the Persian Gulf, etc. The key word is "region." There are numerous cartographic uses for this in Reservoir Engineering as well as maintenance of lease blocks data bases, etc.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>The military has ALWAYS recognized this need and actually published a special book on Zone-to-Zone transformations.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>I seem to write about these valid rational reasons periodically, and I think I do so in this discussion list.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>If you don't want to implement this sort of thing and are looking for a reason not to do so, use sunrise tomorrow as an excuse.</FONT></DIV>
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<DIV dir=ltr><FONT size=2>Cliff Mugnier</FONT></DIV>
<DIV dir=ltr><FONT size=2>LOUISIANA STATE UNIVERSITY</FONT></DIV></DIV>
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<FONT face=Tahoma size=2><B>From:</B> proj-bounces@lists.maptools.org on behalf of support.mn@elisanet.fi<BR><B>Sent:</B> Tue 26-Aug-08 07:35<BR><B>To:</B> PROJ.4 and general Projections Discussions; geraldi.evenden@gmail.com<BR><B>Subject:</B> Re: [Proj] Extended range TM usage<BR></FONT><BR></DIV>
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<P><FONT size=2>"Gerald I. Evenden" <geraldi.evenden@gmail.com> wrote:<BR><BR>> My question is can anyone supply a rational reason for the practical use of an<BR>> elliptical TM projection with extended longitude range.<BR><BR>How practical is that, I don't know, but there is the situation where an user<BR>is zooming out a view so much that a very large area is visible. There can rise<BR>a situation where those extreme areas should be shown somehow. The<BR>accuracy does not matter in that case, since it is only show in relation with<BR>that middle section which is the main focus.<BR><BR>This same situation applies basicly to all projections. Sometimes users zoom<BR>out the views very much and the extreme areas should be shown somehow.<BR>Sometimes clipping them away, or projecting to some limiting line, might be<BR>as good alternative. But my opinion is that it is better to show something than<BR>nothing even if it is a bit unaccurate.<BR><BR>If somebody wants to have more aggressive limiting, he might use the error<BR>mechanism, where the library warns him about the error getting too large<BR>and that particular solution might start to clip those areas away.<BR><BR>Regards: Janne<BR><BR>_______________________________________________<BR>Proj mailing list<BR>Proj@lists.maptools.org<BR><A href="http://lists.maptools.org/mailman/listinfo/proj">http://lists.maptools.org/mailman/listinfo/proj</A><BR></FONT></P></DIV></BODY></HTML>